Caption: Ulcerative colitis, gross specimen. Ulcerative colitis is inflammation of the colon that begins as a disease of the lining of the rectum. It can extend to involve part of, or most of, the large intestine, seen here as ulceration, haemorrhage, and numerous pseudopolyps (regions of remaining intact tissue). Risk of developing colorectal cancer is significantly increased in someone who has had extensive ulcerative colitis for over ten years. Bloody diarrhoea with mucus may be a symptom of chronic conditions.